Split and side-ported catheter devices

ABSTRACT

A catheter for use in medical applications is disclosed. The catheter comprises tubing with a tip hole at one end and an end portion at the other end. Fluid exits the catheter at the tip hole thereof. One or more alternative fluid pathway(s) are provided on the sidewall of the catheter to permit outflow of fluid medication from the catheter to ensure proper delivery of the medication to the intended target area, particularly when the tip opening is occluded or restricted for any reason.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/370,714, filed Jul. 3, 2014, which is based on PCT Patent ApplicationNo. PCT/US13/020342, filed Jan. 4, 2013, which claims priority to U.S.Provisional Patent Application Ser. No. 61/583,564, filed Jan. 5, 2012,the disclosure of which is incorporated herein by reference in itsentirety.

FIELD OF THE INVENTION

The present invention relates generally to catheters used in medicaltreatment and methods of manufacture thereof.

BACKGROUND OF THE INVENTION

A conventional peripheral or intravenous catheter assembly 1 isillustrated in FIG. 1 in cross-section. The assembly 1 includes a wedge3, usually made of a hard substance such as metal or a rigid plastic andhaving a funnel shape, to which an end portion 6 of the catheter tubing4 is frictionally attached to connect the catheter tubing 4 to the wedge3 and a catheter hub or adapter 2. The wedge 3, to which the cathetertubing 4 has been attached, is secured to the hub or adapter 2 to formthe catheter assembly 1. Fluid exits the tip 5 of the catheter tubing 4.Although the type of catheter assembly illustrated in FIG. 1 is for aconventional intravenous catheter assembly, the manner of attachment ofthe catheter can be similar in non-intravenous catheter assemblies, forexample, for use in a subcutaneous infusion set. That is, in asubcutaneous infusion set, a catheter and a wedge can be secured to abase to form a catheter assembly.

FIGS. 2-4 illustrate a conventional infusion set 10 that is used todeliver insulin to a diabetic patient from an insulin pump (not shown).As illustrated in FIG. 2 , the infusion set 10 includes a hub or fluidconnector 22 that detachably connects with a base 12 (see FIG. 4 ), afluid tubing set 16 and a connector 18 that attaches to a pump. FIGS. 3and 4 illustrate the conventional infusion set 10 in which the line set20, which includes the hub 22 and the fluid tubing set 16, is attachedto or detached from the base 12. The base 12 includes an infusionadapter 17 for connecting with the fluid connector or hub 22. Anadhesive pad 15 is attached to the base 12 to secure the base to auser's skin. The catheter 14 is attached to the base 12, for example,with a wedge (not shown). The catheter 14 is similar in shape to thatwhich is more clearly illustrated in FIG. 1 . It is noted, however, thatcatheters for infusion sets (for example, subcutaneous or intradermal)target layers of the skin, and are generally shorter than intravenouscatheters.

One type of conventional infusion set is sold as the Quick-Set® infusionset by Medtronic. In such devices, the infusion set includes a catheterassembly connected to a pump (e.g. MiniMed Paradigm® insulin pump byMedtronic) via a tubing set, and a separate insertion device insertsand/or attaches the catheter assembly to a user via an introducer needleprovided as a part of the infusion set. The catheter assembly can alsobe inserted manually into a user's skin. The infusion set and insertiondevice can also be combined, as in the Mio® infusion set sold byMedtronic, which is an “all-in-one” design that combines the infusionset and insertion device into one unit.

Another type of insulin infusion device known as a “patch pump” has alsobecome available. Unlike a conventional infusion pump, a patch pump isan integrated device that combines most or all of the fluid componentsin a single housing that is adhesively attached to an infusion site, anddoes not require the use of a separate infusion (tubing) set. A patchpump adheres to the skin, contains insulin (or other medication), anddelivers the drug over a period of time, either transdermally, or via anintegrated subcutaneous catheter. Some patch pumps communicate with aseparate controller device wirelessly (such as one sold under the brandname OmniPod®), while others are completely self-contained. Bothconventional pump infusion sets and patch pumps need to be reapplied ona frequent basis, such as every three days, as complications mayotherwise occur.

In all such devices that have flexible catheters, the flexible catheteris inserted into the skin by means of an introducer needle, as is wellknown in the art. Once the introducer needle is removed, generallythrough the catheter, the catheter is enabled to deliver insulin. But,when the catheter is attached to a user, the catheter can becomeoccluded. In other words, the tip of the catheter, from which insulinflows out to the user, becomes obstructed due to the formation of ablockage, such as tissue inflammation. In addition, the catheter maydevelop kinking, such that the catheter becomes snagged, knotted, orsharply bent to form a kink that impedes or blocks fluid flow out of thetip of the catheter.

Kinking is considered to be the cessation of flow through the catheter,due to mechanical causes, such as sliding back (accordion or bellows) orfolding back on the introducer needle during insertion. This failuremode could be the result of insufficient interference between the innerdiameter of the catheter and the outer diameter of the introducerneedle. In addition, kinking may also occur during deployment fromhaving a blunt end on the lead end of the catheter, which may causeexcess force to be transmitted to the catheter as the catheter initiallypenetrates the outer surface of the skin. Similarly, excessive bounce orvibration in the insertion mechanization may also result in excessiveforce being transmitted to the catheter.

Occlusion is the cessation of flow due to biologic or pharmacologiccauses and/or mechanical obstruction of the catheter tip by tissuestructures, as described above, and these failures typically occurduring the use cycle. Depending on the level of irritation caused by thecatheter and the movement allowed by the catheter adapter/hub, thetissue can become inflamed as part of a foreign body response, resultingin reduced insulin uptake. Further, there is a tendency for insulin tocrystallize when flow is reduced to a minimum (low basal flow) ortemporarily stopped, e.g. for bathing, swimming or extended periods,during which time the infusion set is disconnected from the pump.Insulin crystallization that is allowed to proliferate will ultimatelyocclude the catheter to a point at which the required pump pressure canexceed the normal flow conditions of the pump and trigger an alarm.

The tip of the catheter can also be blocked without inflammation ofsurrounding tissue. For instance, the application of an external forceto the infusion site, can cause the open end of the catheter to pressagainst tissue structures in the body, resulting in an occlusion. Thisphenomenon has been demonstrated in model tests in which a slight forceis applied to the infusion hub in a downward direction, and it can beobserved, via fluoroscopy, that the catheter is occluded at the tip.

It is highly desirable, to minimize the risks of occlusion, kinking, andother complications such as tissue inflammation and foreign bodyresponse, while maintaining a degree of comfort to the user, becauseonce the catheter becomes fully or partially blocked, infusion therapycannot take place at all, or can be reduced below target flow rates.

Soft plastic catheters are prone to kink or occlude with normal wear,while the rigid catheters are often found to be uncomfortable to theuser, because the rigid catheter tends to move around within the tissueof the user. Both soft plastic catheters and rigid catheters can alsoexhibit other undesired complications such as tissue inflammation andforeign body response.

Kinking of the catheter can also occur during the infusion or use cycle.A typical cause of this failure is the placement of the catheter intotissue which undergoes significant movement during physical activity. Inaddition, conditions that cause deformation of the catheter maycontribute to kinking.

Insulin infusion devices currently available on the market generallyincorporate either a flexible catheter (made of soft materials, such assoft plastic, fluorinated polymers, Teflon®, and so forth) or a rigidcatheter, such as a stainless steel cannula.

A rigid cannula has a sharp tip, which is used to pierce the skin,similar to an introducer needle in a conventional inserter. Suchproducts are recommended for individuals who have a high incidence ofcatheter kinking and are not recommended for use beyond two days,because they can occlude for the reasons mentioned above.

Accordingly, a need exists for an improved catheter design andconstruction that, in the event the catheter becomes occluded, allowsinfusion to continue to take place at the target area or tissue as wellas reducing instances of kinking and/or occlusion.

SUMMARY OF THE INVENTION

Among the objects of the present invention are to provide cathetersconfigured and arranged to optimize fluid flow out of the catheter whilemaintaining column strength for catheter insertion, axial and radialstrength for resistance to deformation, flexibility for user comfort,and tensile strength for durability, insertion and removal.

These and other objects are substantially achieved by providing acatheter assembly wherein the catheter provides one or more exit pathsin addition to the main exit for infusion at the tip of the catheter,and permits proper delivery of insulin doses to the user when ablockage, such as kinking and/or occlusion, occurs.

In one embodiment, the catheter may include an elongate member having asidewall, first and second end portions, and an opening at each of theend portions, a primary fluid pathway through the elongate memberbetween the openings of the end portions of the elongate member, and asecondary fluid pathway in fluid communication with the primary fluidpathway. The secondary fluid pathway includes one or more side ports inthe sidewall of the elongate member. The side port(s) is/are configuredto release, depending on their number, size and location on the elongatemember, controlled amounts of infusate into the skin of a patient.

In another embodiment, the catheter may include an elongate memberhaving a sidewall, first and second end portions, and an opening at eachof the end portions, a primary fluid pathway through the elongate memberbetween the openings of the end portions of the elongate member, and asecondary fluid pathway in fluid communication with the primary fluidpathway. The secondary fluid pathway includes a self-closing opening inthe sidewall of the elongate member.

Another embodiment provides a method of administering infusate via acatheter. The method includes the steps of providing a catheter with anelongate member having a sidewall, first and second end portions, and anopening at each of the end portions, a primary fluid pathway through theelongate member between the openings of the end portions of the elongatemember, and a secondary fluid pathway in fluid communication with theprimary fluid pathway. The secondary fluid pathway includes one or moreside ports in the sidewall of the elongate member. The side ports areconfigured to release controlled amounts of infusate, depending on theirnumber, size and location on the elongate member, into the skin of apatient. The method further includes inserting the catheter into apatient and administering infusate to the patient via one or both theprimary and secondary fluid pathways of the catheter.

Another embodiment also provides a method of administering infusate viaa catheter. The method includes providing a catheter with an elongatemember having a sidewall, first and second end portions, and an openingat each of the end portions, a primary fluid pathway through theelongate member between the openings of the end portions of the elongatemember, and a secondary fluid pathway in fluid communication with theprimary fluid pathway. The secondary fluid pathway includes aself-closing opening in the sidewall of the elongate member. The methodincludes inserting the catheter into a patient and administeringinfusate to the patient via one or both the primary and secondary fluidpathways of the catheter.

Another embodiment provides an infusion system having a base, a hubdetachably attached to the base, and a pump. The system includes a fluidtubing set that connects the pump and the base and a catheter with aprimary fluid pathway through an elongate member, a secondary fluidpathway at in fluid communication with the primary fluid pathway. Thesecondary fluid pathway includes one or both of a side port and aself-closing opening in a sidewall of the elongate member.

Additional and/or other aspects and advantages of the present inventionwill be set forth in the description that follows, or will be apparentfrom the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The various objects, advantages and novel features of the exemplaryembodiments of the present invention will be more readily appreciatedfrom the following detailed description when read in conjunction withthe appended drawings, in which:

FIG. 1 is an enlarged cross-sectional view of an end portion of aconventional peripheral or intravenous catheter assembly;

FIG. 2 is a perspective view of a conventional infusion set;

FIG. 3 is a top view of the infusion set of FIG. 2 ;

FIG. 4 is a top view of the conventional infusion set of FIG. 2 in whichthe line set is detached from the base;

FIG. 5 is front view of a catheter that is provided with a split on asidewall in accordance with an embodiment of the present invention;

FIG. 6 is a cross-sectional view of the catheter of FIG. 5 ;

FIG. 7 is an enlarged view of the tip of the catheter of FIG. 5 , withthe split shown in a closed position;

FIG. 8 is an enlarged view of the tip of the catheter of FIG. 5 , withthe split shown in an open position;

FIGS. 9-11 illustrate various split catheter configurations inaccordance with embodiments of the present invention;

FIG. 12 is a perspective view of a catheter that is provided with asingle side port in accordance with an embodiment of the presentinvention;

FIG. 13 is front view of the catheter of FIG. 12 ;

FIG. 14 is a side view of the catheter of FIG. 13 ;

FIG. 15 is a perspective view of a catheter that is provided with threestaggered side ports in accordance with an embodiment of the presentinvention;

FIG. 16 is front view of the catheter of FIG. 15 ;

FIG. 17 is a right side view of the catheter of FIG. 16 ;

FIG. 18 is a left side view of the catheter of FIG. 16 ;

FIG. 19 is a perspective view of a catheter that is provided with asingle through hole in accordance with an embodiment of the presentinvention;

FIG. 20 is front view of the catheter of FIG. 19 ;

FIG. 21 is a side view of the catheter of FIG. 20 ;

FIG. 22 is a perspective view of a catheter that is provided with a twothrough holes on the same plane in accordance with an embodiment of thepresent invention;

FIG. 23 is front view of the catheter of FIG. 22 ;

FIG. 24 is a side view of the catheter of FIG. 23 ;

FIG. 25 is a perspective view of a catheter that is provided with twothrough holes on different planes in accordance with an embodiment ofthe present invention;

FIG. 26 is front view of the catheter of FIG. 25 ;

FIG. 27 is a side view of the catheter of FIG. 26 ;

FIG. 28 is a perspective view of a catheter that is provided with twothrough holes of a larger diameter on different planes in accordancewith an embodiment of the present invention;

FIG. 29 is front view of the catheter of FIG. 28 ;

FIG. 30 is a side view of the catheter of FIG. 28 ;

FIG. 31 is a perspective view of a catheter that is provided with acombination of one or more side ports and splits in accordance with aneighth embodiment of the present invention;

FIG. 32 illustrates a front view of a side-ported catheter having twoside ports on different planes, the port configurations having differentdistances between the side port and the tip;

FIG. 32A illustrates a cross-section taken along line 32A-32A of FIG. 32;

FIG. 32B illustrates a cross-section taken along line 32B-32B of FIG. 32;

FIG. 33 illustrates a front view of a side-ported catheter having athrough hole that forms two side ports on a single plane;

FIG. 33A illustrates a cross section taken along lines 33A-33A of FIG.33 ;

FIG. 34 illustrates a front view of a side-ported catheter having asingle side port;

FIG. 34A illustrates a cross section taken along lines 34A-34A of FIG.34 ;

FIG. 35 is a schematic diagram of a pressure system and infusion deviceconfiguration in accordance with an embodiment of the present inventionthat was used in preclinical studies;

FIG. 36 illustrates a front view of a side-ported catheter having asingle side port in accordance with an embodiment of the presentinvention; and

FIG. 36A illustrates a cross section taken along lines 36A-36A of FIG.36 .

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, which are illustrated in the accompanying drawings, whereinlike reference numerals refer to like elements throughout. Theembodiments described herein exemplify, but do not limit, the presentinvention by referring to the drawings. As will be understood by oneskilled in the art, terms such as up, down, bottom, and top arerelative, and are employed to aid illustration, but are not limiting.

The exemplary embodiments described below provide improved catheters foruse with infusion sets and/or patch pumps, or as intravenous orperipheral catheters. For example, in the event of catheter kinking,occlusion and other undesirable complications, such as tissueinflammation and foreign body response that may act to block or reducethe flow of medication fluids out of the catheter to the patient, anadditional pathway or pathways permit the delivery of the medication atthe intended target. Such exemplary embodiments are presented inseparate descriptions, although the individual features of theseembodiments can be combined in any number of ways to meet thetherapeutic needs of the user.

The discussed catheter embodiments are generally flexible, and provide ahigh level of comfort to the user. The catheters can deliver insulin orother medicaments to the target tissue or area even if the main infusionarea, usually at the tip of the catheter, becomes occluded.

FIGS. 5 and 6 illustrate an embodiment of the present invention, inwhich a catheter 30 comprises a length of tubing 33, a tapered tip 32 atone end of the tubing 33 and an end portion 34 at the other end of thetubing 33, away from the tip 32. The tip 32 includes a tip hole 321. Thecatheter 30 includes a cut or split 31 penetrating through its side wallthat is shown to be located at a general location where the tubing 33meets the tip 32. Alternatively, the split 31 can be located anywhere onthe catheter 30 that will ultimately be deployed in the target tissue.FIG. 6 is a cross-sectional view of the catheter 30. FIGS. 7 and 8 areenlarged views of the distal end of the catheter 30 to better illustratethe split 31. FIG. 7 illustrates the split 31 in a closed state and FIG.8 illustrates the split 31 in an opened state. In the open state, thesplit 31 communicates with the internal lumen of the catheter 30.

Other than the tapered tip 32, the tubing 33 has a substantiallyconstant cross-sectional area prior to installation of the tubing 33onto a wedge. Such installation onto a wedge, whether for an intravenouscatheter hub or for a catheter assembly on an infusion set, forms theend portion 34 illustrated in FIGS. 5 and 6 . Although the end portion34 is illustrated as being deformed by a wedge, the wedge itself isomitted from FIGS. 5 and 6 for clarity. According to one embodiment, ifthe tubing 33 is removed from the wedge, the tubing will return to theprevious shape of a tube with a substantially constant cross sectionalarea.

The primary infusion path is via the tip hole 321 and the secondaryinfusion path is via the split 31. This embodiment of the presentinvention allows for a secondary infusion path to open, if the primaryinfusion path becomes occluded or if the flow rate through the primaryinfusion path is insufficient.

The catheter 30 of this embodiment can be an integral part of an insulininfusion set, as illustrated in FIG. 2 , and is modified to include oneor more splits 31 that can be located proximal to the distal tip or tiphole 321 of the catheter 30, preferably at a distance of approximately1.0 mm to 4.0 mm, depending on depth of the targeted tissue layer.According to one embodiment, the split 31 (or splits) has a single axis,which is preferably oriented along the length of the catheter 30. Two ormore of the splits 31 can be crossed, such that two splits 31 can beoriented 90° from each other. Other variations for the splits areenvisioned in which splits can be crossed at various angles, e.g. 30degrees, 45 degrees, etc., and the lengths of the splits can be the sameor different.

FIG. 6 illustrates a single split 31, but the number of splits on acatheter may be plural. A plurality of the splits 31 may also be spacedapart such that they are located 180° around the catheter 30 from eachother, for instance, at the same distance from the distal tip or tiphole 321 of the catheter 30. In addition, the splits 31 can bestaggered, for instance at different distances from the distal tip 321of the catheter 30, and at the same or different circumferentiallocations on the catheter 30. Thus various configurations are envisionedin which one or more splits 31 are located anywhere on the catheter 30.

When the catheter 30 is part of an infusion set, the splits 31 may bepositioned on the catheter 30 to be located within the target tissue,e.g. subcutaneous (SC), intradermal (ID) and/or intramuscular (IM), oncethe catheter 30 has been deployed. In other words, the positions of thesplits 31 may be created to specifically target one or more layers ofthe target tissue.

As illustrated in FIGS. 7 and 8 , the split 31 is configured to openwhen the internal pressure of the catheter 30 reaches a specificthreshold due to the release of insulin into the catheter 30 by theinfusion pump. For example, if the tip hole 321 is blocked, due toocclusion or kinking, thus restricting or preventing the release ofinsulin via the tip hole 321. But the split can open even if there is noocclusion in the tip hole 321.

When the internal pressure within the catheter 30 reaches a specificthreshold (cracking pressure), the pressure causes the split 31 to openand form a secondary infusion pathway, as illustrated in FIG. 8 .Preferably, the cracking pressure for opening the split 31 should begreater than the typical pressure that is encountered within thecatheter 30 during insulin infusion, but lower than the pressurerequired to trip the high pressure alarm in the infusion pump (whichindicates catheter blockage), such that the split 31 will open only ifthe tip hole 321 becomes occluded. Catheter occlusion may be due to oneor more causes, including insulin crystallization, tissue irritation,tissue interference with the catheter tip opening, and kinking of thecatheter.

The cracking pressure for opening the split 31 can be determinedempirically, by varying the length of the split 31, while “dead-ending”or clamping the catheter tip 32 and increasing the internal pressurewithin the catheter 30.

When the cracking pressure for the split 31 has been reached, the split31 will open, as illustrated in FIG. 8 , thereby creating a secondaryinfusion path that opens after the primary infusion path at the distaltip or tip hole 321 has become occluded. It is noted that the catheter30 can slightly deform from its closed shape, as illustrated in FIG. 7 ,to that illustrated in FIG. 8 , when the split 31 is opened to form asecondary infusion pathway. FIG. 8 illustrates deformation of thecatheter tip 32. In this instance, as the split 31 is opened, the tip 32and tubing 33 deform slightly to accommodate the opening of the split31, and it is possible that such deformation may help remove an existingocclusion formed at the tip hole 321.

There are additional advantages to this embodiment of the invention. Ina catheter 30 with one or more splits 31, there is minimal loss ofcolumn strength and virtually no loss of tensile strength in thecatheter 30.

In an embodiment in which there is a plurality of splits 31 in acatheter 30, a split near the tip hole 321 can be designed topreferentially provide infusion upon occlusion at the tip hole 321. Butonce the tip hole 321 occludes, infusion can be sequentially providedthrough the splits, according to increasing degrees of crackingpressure. In other words, with a plurality of splits 31 on the catheter30, each of the splits 31 will have its own cracking pressure, whichwill preferably be different, such that only one split 31 is opened atthat time. If for any reason, the split 31 having the lowest crackingpressure is prevented from opening, the split with the next highestcracking pressure will open, and so on. It is also envisioned, however,that a plurality of splits 31, each having the same cracking pressure,may be placed on the catheter, so that infusion is simultaneouslyprovided to all of the splits at the same time.

Creating one or more splits 31 on a catheter 30 can be made simply andcost effectively. The splits 31 may be cut in the same manner as cutsare made in a split septum, for example, with a laser or knife edge. Thesplits may be of different lengths, but are generally small, in therange of about 0.079 inch (2.0 mm) or less, as illustrated in FIG. 3E.Such a process is quick, inexpensive, and can even be incorporated intothe catheter molding process.

By creating secondary and/or additional infusion paths, a splitcatheter, as illustrated in FIG. 6 , can function to increase thelongevity of the infusion site by providing an alternate, unusedinfusion path that is activated only when the primary infusion pathoccludes or is shut down. The split catheter 30 can be incorporated intoan infusion set, as is illustrated in FIG. 2 , that dispenses insulin toa patient. Where there are a multiple number of splits 31 on a catheter30, the splits can be configured to have increasing cracking pressures,so that the splits 31 can sequentially open if the internal pressure ofthe catheter 30 continues to increase. Such a situation can occur aseach opening is sequentially occluded over time. This configuration canbe made by varying the length of the splits 31 to correspond todifferent cracking pressures, for instance. Although the split 31 isshown as a single split in the wall of the catheter 30, there can beadditional cuts or configurations (e.g. cross-cut to form a cross-spilt)so that the level of internal pressure at which the split 31 opens canbe further controlled by such design.

FIGS. 9-11 illustrate split catheters of varying split designs, alongwith their cross-sectional views. FIG. 9 illustrates a split catheter 30having an “I”-shaped slot or split 31A with a longitudinal length ofabout 0.078 inch (2.0 mm) and lateral lengths of about 0.01 inch (0.25mm). FIG. 10 illustrates a split catheter 30 having a straight slot orsplit 31 with a length of about 0.078 inch (2.0 mm). FIG. 11 illustratesa split catheter 30 having a flap configuration split 31B, thecircumferential length of which extends approximately 60 degrees to 120degrees of the circumference of the catheter 30.

The splits illustrated in FIGS. 9-11 are shown as being formed bystraight line cuts, but they are not limited to such geometry. Thesplits may include curved split shapes, such as a “C”-shaped split,“S”-shaped split or “U”-shaped split (not shown). FIGS. 9-11 illustratea cannula or catheter of approximately 24 gauge, having an outerdiameter of approximately 0.027 inch (0.69 mm) and a wall thickness ofabout 0.004 inch (0.1 mm). The split catheters can be used withconventional insulin pump systems, such as the Animas One Touch Ping,which can provide a normal delivery speed in units (U) per second (s) of0.5-0.9 U/s of insulin and a slow delivery speed of 0.2-0.4 U/s, whereone (1) unit of U-100 insulin is 10 microliters.

The splits 31 can be positioned at different locations on the catheter30, as previously described, and in addition one or more of such splits31 can be substituted for various openings on the catheter, or used incombination thereof, as will be described in the following embodiments.

FIGS. 12-31 also illustrate various embodiments in which secondary oradditional pathways are provided for insulin in addition to the tip holeof the catheter. The embodiments illustrated in FIGS. 12-31 include endportions, like the end portion 34 in FIGS. 5 and 6 . But unlike endportion 34 of FIGS. 5 and 6 , for clarity, the end portions in FIGS.12-31 are shown without the deformation associated with installation ona wedge. These end portions, however, once installed on a wedge, woulddeform similar to the end portion 34 illustrated in FIGS. 5 and 6 .

FIGS. 12-31 illustrate side-ported catheter embodiments. Theseembodiments are subcutaneous catheters that are perforated with one ormore holes extending completely through a side wall of the tubing toform one or more side ports and provide an alternate flow path (i.e.,other than the tip hole) during insulin infusion. Existing insulininfusion subcutaneous catheters allow medicament flow out of the tip ofthe catheter (tip hole). As described previously, the tip hole canbecome occluded by the surrounding tissue that can seal off the tip ofthe catheter during insertion or due to other factors. Catheters mayalso be subjected to kinking or bending during insertion, which may alsolimit insulin flow to the target tissue from the catheter.

When occlusion or kinking occurs to block flow of insulin out of thecatheter tip (tip hole), catheters with one or more perforations, orside ports, allow secondary pathways that will remain open and redirectthe flow of medicaments, such as insulin. Because of this, side-portedcatheters with such secondary pathways ensure that correct dosing to thepatient occurs. In the case of insulin dosing, unexplained high bloodglucose levels and pump occlusion alarms are prevented. In addition, aninfusion site may last longer, thus improving the comfort level to thepatient who need not be subject to additional catheter insertions.

During the development of various perforated catheter embodiments,multiple perforated catheter designs were evaluated that differed inhole sizes, hole locations and catheter materials. These are all factorsthat were observed to affect catheter structural integrity, infusionsite leakage, and insertion reliability. Preferably, to ensure thecatheter port is contained within the subcutaneous space, the perforatedhole 41 should not be closer than 2.5 mm from the surface of the skin(or the thickness of the intra-dermal space). Additionally, the sideholes should be strategically placed in the catheter to ensure thatenough material is provided around the side holes, to prevent collapseof the catheter. During testing of various embodiments of side-portedcatheters, it was discovered that the total side port cross-sectionalarea should be similar to or less than the cross-sectional area at thecatheter tip or the tip hole 421.

In addition to the perforated holes or side ports, other geometries,such as longitudinal splits or crosses (crossed-splits), as discussedabove, may be substituted for the perforated holes or side ports, or maybe used together with the perforated holes. Due to the one or moreside-ported holes on the catheter that provide alternate path or paths,insulin or other fluid medicament coming out of the catheter can infuseinto the patient with low resistance.

The side ports may be created in a manner similar to the earliermentioned splits, i.e., via lasing or mechanical processes. Lasing ispreferred in making the side ports due to their small diameters, butmechanical drilling can produce similar results. In general, lasing ormechanical drilling are preferred processes in forming the side ports,and such processes can be incorporated into the catheter moldingprocess. An advantage of lasing the side ports is that the ports do nothave to be round. In other words, elongated holes or ports with the sameopen area as a round port or hole may improve both the column strengthand the tensile strength of the catheter.

FIG. 12 illustrates an embodiment of the present invention, in which acatheter 40 is provided with a single side port 41. The catheter 40comprises a tubing 43, a tapered tip 42 having a tip hole 421, and anend portion 44 (simplified) opposite the tip 42. The location of theside port 41, as measured from the tip hole 421, can vary according tothe thickness of the desired dermal layer so that infusion can bedelivered to the target tissue layer. FIG. 13 is a front view of thecatheter 40. In an exemplary embodiment, the distance “f” isapproximately 2.0 mm±0.3 mm. FIG. 14 is a side view of the catheter 40.The outer diameter “d” of the catheter 40 is approximately 0.57 mm±0.04mm. The diameter “e” of the side port 41 is approximately 0.15 mm±0.025mm.

FIG. 15 illustrates another embodiment of the present invention, inwhich there are staggered single-side holes 51 that are placed along thelength of the catheter tubing 53, although only one side-hole isillustrated in FIG. 15 due to the orientation of the perspective view.The locations of the holes 51 are more clearly illustrated in FIGS. 16to 18 . FIG. 16 is a front view of the catheter 50. FIG. 17 is a rightside view of the catheter 40, and FIG. 18 is a left side view of thecatheter 40. The staggering angle is not limited to the depicted 90°,and may include other angles, such as 45° or 180°. The outer diameter“g” of the catheter 50 is approximately 0.71 mm±0.04 mm. The diameter“h” of the side port 51 is approximately 0.20 mm.

The catheter 50 comprises a tubing 53, a tapered tip 52 at one end ofthe tubing 53 having an exit hole or tip hole 521, and an end portion 54(simplified) opposite the tip 52. The staggered layout of the perforatedholes 51 provides sufficient strength for the catheter 50 that thecatheter 50 will not easily collapse during insertion. Further, thisarrangement provides for sufficient catheter material to be formedaround each of the three staggered holes 51. Each of the perforatedholes 51 are shown as having different distances from the tip hole 521,such as “””=3.0 mm, “j”=2.0 mm, and “k”=4.0 mm, as is illustrated inFIG. 16 to FIG. 18 . The number of staggered perforated holes 51 or sideports can be two, three, or more.

FIG. 19 illustrates another embodiment, in which a catheter 60 includesa single through-hole 61 that extends from one sidewall of the tubing 63through an opposite side thereof, as is more clearly illustrated inFIGS. 20 and 21 . The catheter 60 includes a tubing 63, a tapered tip 62at one end of the tubing 63, a tip hole 621, and an end portion 64(simplified) at an opposite end of the tip 62. The two holes 61 formedby the single through-hole have the same distance from the tip hole 621,as is illustrated in FIG. 20 . Such arrangement provides for sufficientstrength of the catheter 60 to withstand the impact forces duringcatheter insertion. The outer diameter “D1” of the catheter 60 isapproximately 0.71 mm. The diameter “m” of the holes 61 is approximately0.25 mm. The distance “n” from the tip hole 621 to the holes 61 isapproximately 3.0 mm.

FIG. 22 illustrates another embodiment in which there are twothrough-holes that form four side holes 71 equally distanced from thetip hole 721, as illustrated in FIGS. 23 and 24. The diameter “p” of theside holes 71 is approximately 0.25 mm. The catheter 70 includes atubing 73 with a tapered tip 72 on one end with a tip hole 721, and anend portion 74 (simplified). It is noted that due to the presence of thefour side port holes 71 along the same plane, such a catheter design maybe more susceptible to collapsing at the plane of the perforationsduring insertion of the catheter 70. This is generally due to thereduced amount of material between the holes 71, resulting in a designthat may be structurally weak. But such a layout in which the perforatedholes are at or close to the tip 72 is desirable to reduce the risk ofinfusate leakage if the desired infusion site is proximate to the tiphole 721. The distance “q” between the side holes 71 and the tip hole721 is approximately 2.03 mm. Structural integrity can be maintained byusing stronger or thicker material for the catheter.

FIG. 25 illustrates an embodiment of the present invention in whichthere are two staggered through-holes that form four side holes or ports81. FIG. 26 is a front view of the catheter 80 and FIG. 27 is a sideview of the catheter 80.

In this embodiment, a first set of two of the through-holes or sideports 81 are located at the same plane and a second set of two otherside ports 81 are located at a different plane. In other words, athrough hole forms two side ports. The diameter “s” of the side ports 81is approximately 0.15 mm. The holes are located so that the first set ofthe through-holes are distanced equally from the tip hole 821 (distance“t”=3.0 mm), and the second set of through-holes 81 are spaced equallyfrom the tip hole 821 (distance u=2.0 mm), as illustrated in FIGS. 26and 27 . The outer diameter “r” of the catheter 90 is approximately 0.71mm±0.04 mm. Such an arrangement provides for sufficient cathetermaterial to be formed around each of the holes 81 to maintain structuralintegrity of the catheter 80 during use. The catheter 80 includes atubing 83, a tip 82 at one end of the tubing 83, with a tip hole 821,and an end portion 84 (simplified) opposite the tip 82.

FIG. 28 illustrates another embodiment of the present invention in whichtwo staggered through-holes are formed on the catheter 90, in order toform four side holes 91. The through-holes are formed on differentcircumferential orientations. The embodiment of FIG. 28 is similar tothe embodiment of FIGS. 25-27 , differing only in the diameter of theside holes. FIG. 29 is a front view of the catheter 90 and FIG. 30 is aside view of the catheter 90. In this embodiment, the outer diameter “v”of the catheter 90 is approximately 0.71±0.04 mm. The diameter of theside port “w” is approximately 0.25 mm. The distances “y” and “z” fromthe sets of side ports 91 are approximately 3.0 mm and 2.0 mm,respectively.

In general, the size of the side ports and the location thereof on thecatheter can be varied. The locations of the side ports correspond to acatheter for which the tip is generally deployed to a depth of about 6.0mm from the skin's surface. The side ports can be on the tubing or atthe tip, near the tip hole, or at a junction between the tip and thetubing, or at any other location on the catheter. As the introducerneedle of an infusion set penetrates the skin, the skin initiallyresists penetration and deforms in the shape of an inverted tent (knowncommonly in the art as “tenting”). The size of the side holes or portsand their locations relative to the catheter tip are factors that shouldbe taken into account to reduce insertion problems, such as excessivetenting, as well as leakage from the infusion site. Because theintroducer needle is inserted through the catheter for the purpose ofinserting the catheter into the skin, the dimensions and configurationsof the catheter can affect the amount of tenting. Generally a catheterwith thin walls may cause less tenting than a catheter with thickerwalls. Excessive tenting may result in improper insertion of thecatheter at the desired depth of the skin. Leakage at the infusion sitemay occur if the catheter is not properly inserted to the targetedtissue layer of the skin, and excessive tenting can cause such leakage.

FIG. 31 illustrates another embodiment of the present invention in whichthe catheter 100 includes a side port 110, a single split 111, a crosssplit 113 and a split hole 112 (in which a hole is formed on a split).This embodiment illustrates that the various openings, including sideholes and splits may be used in combination to form secondary oradditional pathways in a catheter. As with other embodiments, thecatheter 110 includes a tubing 130, a tapered tip 120 having a tip hole121, and an end portion 140 (simplified) opposite the tip 120.

A preferred embodiment of a side ported catheter for delivery intosubcutaneous tissue has a deployment depth of about 6 mm, with catheterport(s) within 2 mm of the catheter tip (opening), and ideally within 1mm of the catheter tip. Such a catheter is preferably between 24 G and28 G and made of polyurethane, polyolefin or fluorinated polymer such aspolytetrafluoroethylene (PTFE) or fluorinated ethylene propylene (FEP).The catheters can also be made of silicone and various additives can beincorporated to improve mechanical strength and other properties. FEP isgenerally preferred over PTFE due to its thermoplastic properties thatimprove the effectiveness of the catheter forming process. It ispreferred that the side ports on the catheter are formed by lasing ormechanical drilling, processes that are familiar to those skilled in theart. The formation of the side ports can also be incorporated into thecatheter molding process.

Preclinical studies were conducted to determine the effectiveness ofside ported catheters. From the preclinical studies, it was discoveredthat adding side ports to catheters significantly reduced the rate ofocclusion alarms with generic ambulatory insulin infusion pumps that arecommercially available. The side ported 6 mm catheters were tested alongwith un-ported, conventional 6 mm catheters. The conventional 6 mmcatheters experienced occlusions alarms in 4 out of 16 pump devicestested on swine. In contrast, side ported 6 mm catheters experiencedpump occlusion alarms in 0 of 48 pump devices, when tested under thesame conditions.

In the preclinical studies mentioned above, side ported catheters ofthree different configurations were tested (see FIGS. 32-34 ). The sideport catheter illustrated in FIG. 32 includes two ports that are ondifferent planes, with the ports being staggered by 180 degrees andbeing 1.0 mm and 1.5 mm from the tip (x₁=1.0 mm; x₂=1.5 mm). The sideported catheter illustrated in FIG. 33 includes a through-hole on thesame plane that forms two side ports (x₁=1.0 mm from the tip). The sideported catheter illustrated in FIG. 34 includes a single side port(x₁=1.0 mm from the tip). The configurations above are similar to thosethat are illustrated in FIGS. 12-21 , except that the side ports arelocated on the tapered distal portions of the catheter and closer to thetip opening.

FIG. 35 is a schematic diagram of an in-line infusion pressure datacollection system and its configuration with infusion sets that was usedin preclinical testing. FIG. 35 shows a pressure data logger interfacedwith a pressure transducer that is placed in-line via Luer connectorswith the infusion set and an adapter to the reservoir containing theinfusate. As the infusion pump operates, the pressure data logger storesthe in-line infusion pressure profile. Rising infusion pressureindicates a flow restriction or occlusion.

In one preclinical study, swine were placed under anesthesia and 64infusion sets (n=16 each of standard, non-ported conventional 24 G, 6.0mm infusion catheters and n=16 each of 3 configurations of side portedcatheters illustrated in FIGS. 32, 33 and 34 ) were inserted in a 4×4grid pattern. All infusion sets were connected to in-line infusionpressure data loggers described in FIG. 35 . A specific infusion profileof bolus (high infusate delivery over a short period of time) and basal(low infusate delivery over extended periods of time) infusion wasdelivered over the course of this study. Flow interruptions asinterpreted from the infusion pressure profiles were significantlydecreased in each side-ported catheter configuration relative to thestandard catheter configuration.

There was an 83% reduction in the number of flow interruptions and a 97%reduction in percent of total infusion time with flow interrupted forinfusion sets with the side-ported catheters as compared with infusionsets with standard (non-ported) catheters. Visual inspection of thepressure profile plots also led to the following observations: peakbolus pressures were lower for ported catheters than non-ported ones;overall basal infusion pressures were lower for ported catheters thannon-ported ones; and the insertion effect (flow interruption uponinsertion as indicated by a rise in infusion pressure) during the first4 hour basal infusion period was reduced or eliminated in all of theside-ported catheter configurations relative to the non-portedcatheters.

The preclinical studies above confirmed that standard catheters withsingle openings at their tip (without any side-port(s)) experiencefrequent flow interruptions that result in non-delivery of insulin overdurations that range from minutes to hours. In a swine study conductedusing infusion catheters over a nine hour period, the mean percent timethat flow was interrupted for control catheters (un-ported) was 34.5percent. In contrast, the mean percent time that flow was interrupted inported catheters was less than one (1.0) percent in all configurationstested. The preclinical studies above confirmed the improvements of theside-ported catheters over the standard non-ported catheters.

Further preclinical studies on swine confirmed that the distance of theside-port(s) from the catheter tip hole affected the deposition of theinfusate. A fluoroscopy study in a swine model was conducted todetermine the boundary conditions of side-port locations for successfulsubcutaneous infusion through evaluation of single side-ported catheterswith side-ports placed over a range of distances (0.5-4.0 mm) from thecatheter tip hole, as illustrated in FIG. 36 . The single side-portedcatheters were numbered 1 to 4. In the preclinical studies, cathetersthat protrude into the skin with a 6.0 mm length and side-port(s) at 0.5mm or 1.0 mm from the catheter tip hole resulted in infusate depotlocations that were indistinguishable from un-ported catheters and didnot result in infusate leakage. Catheters with side-ports at 2.0 mm fromthe catheter tip had shallower deposition, but also deliveredsubcutaneously without leakage. However, catheters with ports at 4.0 mmfrom the catheter tip experienced significant leakage between thecatheter and the skin surface.

In the study of the single side-ported catheters, a typical one beingillustrated in FIG. 36 , the catheters were each connected to areservoir filled with Iohexol in a generic ambulatory insulin infusionpump. Each infusion device with a side-ported catheter was insertedusing manual insertion into the flank of an anesthetized swine. Once theinfusion device was inserted, a 10U bolus of Iohexol was delivered whileviewing the infusion site under a fluoroscope. It was observed that thefrequency of leakage between the catheter and skin increases as theside-port distance (x) increases from the catheter tip hole. A catheter(port 4 mm) having a side-port 4 mm from the tip hole had 6 of the 7leakages observed in the study. Port 2 mm and Port 3 mm devices resultedin significantly shallower depots than the control, Port 0.5 mm, andPort 1 mm devices. The study indicated that port placement (x) within1.0 mm from the catheter tip hole or less on a 6.0 mm catheter resultsin infusate deposition that is similar to catheters with only a singlehole in the catheter tip.

Additional preclinical studies indicated that the catheter material andwall thickness may affect the performance of catheters in general andparticularly affects the performance of catheters with side port(s).Thinner catheter tip designs can result in catheter tip deformation thatleads to permanent occlusion of the catheter. A minimum wall thicknessfor a side-ported catheter is preferred to maintain catheter tippatency. Preclinical studies were performed on single side-ported 24Gand 28G catheters. For a 24G catheter, a minimum wall thickness at thetip of 0.003 inch (0.076 mm) is preferred for PTFE and FEP cathetermaterials. The catheter material can include silicone or other suitablematerial. A catheter wall thickness at the tip of 0.002 inch (0.051 mm)resulted in catheter deformation and occlusion in 24G, 26G, and 28Gexperimental and commercial devices.

Catheters having a secondary fluid pathway, such as a side port, may beless likely to bend or kink when attached to a patient. In addition,deformations at the catheter tip appear to be less than with ordinarycatheters, upon use. Moreover, an advantage of a split catheter (i.e.,one having one or more splits on the sidewall of the catheter) is thatbecause the splits are generally flush with the surface of the sidewall,the split catheter is less likely to snag on the patient's skin duringinsertion.

The configuration of a catheter having a plurality of side openings orsplits or a combination thereof may be used in catheters that areinserted into the user's skin at an angle (e.g. 30 degrees), as opposedto a vertical insertion. An advantage to this configuration is that theskin can more readily absorb infusate due to the additional number ofside openings or slits along an elongated length.

Although only a limited number of exemplary embodiments of the presentinvention have been described in detail above, those skilled in the artwill readily appreciate that many modifications are possible in theexemplary embodiments without materially departing from the novelteachings and advantages of this invention. Accordingly, all suchmodifications are intended to be included within the scope of thisinvention as defined in the appended claims and their equivalents.

1. A catheter comprising: a flexible elongate member extending from aproximal end to a distal end comprising a sidewall, a proximal endportion having a first opening and a distal end portion having a secondopening; a primary fluid pathway through the elongate member between thefirst opening and the second opening; and a secondary fluid pathway influid communication with the primary fluid pathway; wherein the elongatemember comprises a non-tapered portion extending from the proximal endportion to a tapered portion, and wherein the tapered portion extends tothe distal end portion; wherein the secondary fluid pathway comprises aslit in the sidewall extending from the non-tapered portion to thetapered portion.
 2. The catheter as claimed in claim 1, wherein the slitremains closed while a fluid pressure within the catheter remains belowa threshold fluid pressure, and opens when the fluid pressure within thecatheter exceeds the threshold fluid pressure.
 3. The catheter asclaimed in claim 1, wherein the catheter is integrally former with aninfusion set.
 4. The catheter as claimed in claim 1, wherein thecatheter comprises plastic material.
 5. The catheter as claims in claim1, wherein the threshold fluid pressure is less than an alarm pressureof an infusion pump in fluid connection with the catheter; and greaterthan a predetermined typical fluid pressure during infusion.
 6. Aninfusion system comprising: a hub detachably connected to a base; afluid tubing set comprising a connector adapted to connect to a fluidsource; and a catheter in fluid connection with the fluid tubing set;wherein the catheter comprises: a flexible elongate member extendingfrom a proximal end to a distal end comprising a sidewall, a proximalend portion having a first opening and a distal end portion having asecond opening; a primary fluid pathway through the elongate memberbetween the first opening and the second opening; and a secondary fluidpathway in fluid communication with the primary fluid pathway; whereinthe elongate member comprises a non-tapered portion extending from theproximal end portion to a tapered portion, and wherein the taperedportion extends to the distal end portion; wherein the secondary fluidpathway comprises a slit in the sidewall extending from the non-taperedportion to the tapered portion.
 7. The infusion system as claimed inclaim 6, wherein the slit remains closed while a fluid pressure withinthe catheter remains below a threshold fluid pressure, and opens whenthe fluid pressure within the catheter exceeds the threshold fluidpressure.
 8. The infusion system as claimed in claim 6, wherein thecatheter comprises plastic material.
 9. The infusion system as claims inclaim 6, wherein the threshold fluid pressure is less than an alarmpressure of an infusion pump in fluid connection with the catheter; andgreater than a predetermined typical fluid pressure during infusion.